Several years ago I was in the same quandary. LHT had recently been introduced and 520's were still made in the USA. Tried both, plus a Cannondale [USA also]. Have an odd body shape & size; short legs and arms, long torso. The LHT specs fit me better than 520. I was fortunate to have bike shops not too far apart stocking both.
I rode the LHT, it was nice - this was the bike I though I should get. Then I rode the 520 - wow it felt nice. Then I rode each on the same afternoon, loaded and unloaded. I went home with the 520, still going well thousands of km later. I did get steerer tube extension for the 520, raised the handlebars about 3 cm to a very comfortable spot for me - it has worked well.